Experimental investigation of photonic band gap influence on enhancement of Raman-scattering in metaldielectric colloidal crystals J. Appl. Phys. 112, 084303 (2012) Composition, nanostructure, and optical properties of silver and silver-copper lusters J. Appl. Phys. 112, 054307 (2012) Influence of alloy inhomogeneities on the determination by Raman scattering of composition and strain in Si1-xGex/Si(001) layers J. Appl. Phys. 112, 023512 (2012) Plasmon coupling in circular-hole dimers: From separation-to touching-coupling regimes J. Appl. Phys. 112, 013113 (2012) Correlation between reflectivity and resistivity in multi-component metallic systems Appl. Phys. Lett. 101, 011902 (2012) Additional information on J. Appl. Phys. The optical constants n and k of holmium (Ho) films were obtained in the 3-1340ÀeV range from transmittance measurements performed at room temperature. Thin films of Ho with various thicknesses were deposited by evaporation in ultra high vacuum conditions and their transmittance was measured in situ. Ho films were deposited onto thin C-film substrates supported on high transmittance grids. Transmittance measurements were used to obtain the extinction coefficient k of Ho films. The refractive index n of Ho was calculated with KramersÀKrönig analysis; in order to do this, k data were extrapolated both on the high and on the low energy parts of the spectrum by using experimental and calculated k values available in the literature. Ho, similar to other lanthanides, has a low-absorption band below the O 2,3 edge onset; the lowest absorption was measured at $22 eV. Therefore, Ho is a promising material for filters and multilayer coatings in the energy range below the O 2,3 edge in which most materials have a large absorption. Good consistency of the data resulted from the application of f and inertial sum rules.